Optical networks and the like are deploying control plane systems and methods that span multiple layers (e.g., wavelength division multiplex (WDM), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), Optical Transport Network (OTN), Ethernet, and the like). Control plane systems and methods provide automatic allocation of network resources in an end-to-end manner. Exemplary control planes may include Automatically Switched Optical Network (ASON) as defined in G.8080/Y.1304, Architecture for the automatically switched optical network (ASON) (February 2005); Generalized Multi-Protocol Label Switching (GMPLS) Architecture as defined in Request for Comments (RFC): 3945 (October 2004) and the like; Optical Signaling and Routing Protocol (OSRP) from Ciena Corporation of Linthicum, Md. which is an optical signaling and routing protocol similar to PNNI (Private Network-to-Network Interface) and MPLS; or any other type control plane for controlling network elements at multiple layers, and establishing connections therebetween. Control plane systems and methods use link management protocol(s) to discover peers on topological links. These protocols exchange information over a dedicated and well known communication channel with peers on opposite ends of the communication link. Communication exchange establishes peer adjacency, type, capacity, and the like of topological link between peers. Topological link information is then advertised to all nodes that perform path computation in the network.
In a digital networks (e.g., SONET, SDH, OTN, etc.), understanding network topology and capacity on each topological link provides a basis for path computation. However, due to the analog nature of a photonic network, path computation in the photonic network requires additional information identifying photonic attributes of each link which are necessary for computation of optical reach. In conventional photonic networks, photonic information is collected via a Network Management System (NMS), Element Management System (EMS), or the like, using a centralized method of data collection from the network. Centralized collection of photonic network layer information from photonics links requires that the NMS, EMS, etc. collect the information from each node individually. This means that an NMS, EMS, etc. is required in networks managed by a distributed control plane. Disadvantageously, such data collection is typically time consuming and involves off-line computation algorithms. Hence, these conventional methods are in conflict with real-time nature of control planes, and implies a longer overall system response time to changes in network topology. In most cases, network updates via the NMS, EMS, a planning system, etc. require that an operator or planner gets involved.
While control plane standard bodies describe protocols for control plane signaling and routing and a path computation device, they do not address how photonic data should be collected and distributed in the control plane. For example, a conventional GMPLS networks discover network topology, but not photonic layer attributes. Without photonic layer attributes, a path computation algorithm cannot compute and validate wavelength reach. Without knowing amplifier type, fiber types, amplifier gains settings, power levels, and others, the algorithm may only work from pre-computed tables or manually entered data, and will not be able to accurately compute reach since it will be lacking enough input parameters. Without distributed photonic data collection and distribution, a Path Computation Element (PCE) has to use a centralized photonic layer data collection described above.
Unique to photonic networks, the photonic network layer includes various optical components such as optical amplifiers, and the configuration of the optical amplifiers is typically fixed, i.e. it has a fixed set of inputs and outputs and a fixed set of connections therebetween. Hence, from the perspective of the control plane, the optical amplifier nodes are irrelevant since they do not provide flexible switching at a data plane layer. However, the Optical Multiplex Section (OMS) and Optical Transmission Section (OTS) relationship is relevant in order to understand shared risk link information. Note, OMS and OTS are photonic layers defined in Optical Transport Network (OTN) such as in ITU Recommendations G.872, G.707, G.798, G.9591, and G.874, the contents of each are incorporated by reference herein. In a GMPLS network, the GMPLS network discovers links to neighbors. In a photonic network, each amplifier terminates an OTS link, and hence each optical amplifier then needs to discover neighbors and advertise these links to the rest of the network. Hence, in a conventional GMPLS network, each optical amplifier has to run a full protocol stack, and have enough processor performance and memory to hold topology for the entire network.
Disadvantageously, placing a full control plane stack at each optical amplifier has two side effects. First, a large number of network nodes inhibits scaling. For example, an OMS link may have up to 30 or more optical amplifiers. If each optical amplifier is a control plane node, the total number of nodes in the network goes up by an order of 10 or more. Such a large number of network nodes has a very large impact of network scalability, mainly impacting the scalability of network flooding. Secondly, each amplifier control processor has to be capable of holding full network database. Thus, as the network and the network's associated meshing of nodes grows, memory and processor performance requirements grow exponentially.